The short version of wound model fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2026-01-02. Anything still debated is marked as such rather than presented as settled.
Discussion of TB-500 appears in several distinct literatures that rarely cite one another. Peer-reviewed studies usually describe in vitro assays or small animal experiments and are cautious about extrapolation. Veterinary and sports communities circulate anecdotal reports with limited methodological detail. Commercial listings add a third layer, often using the name interchangeably with thymosin beta-4 even though the two molecules differ in size and sequence. Regulatory status varies by country, and the compound is not a licensed medicine in most jurisdictions, so readers comparing sources should check which molecule and which purity each source actually describes.
TB-500 is a synthetic seven-residue peptide whose sequence, LKKTETQ, matches the N-terminal actin-binding region of thymosin beta-4. It is usually supplied in an N-terminally acetylated form, a modification that blocks the free amino terminus and can influence behavior in solution. In the research literature the same sequence appears under several names, including thymosin beta-4 fragment and shortened thymosin beta-4. Because it is a short peptide rather than the full 43-residue parent protein, its measured properties differ from those reported for thymosin beta-4 as a whole, and the two are not interchangeable in experimental design.
Regulatory status differs by country, but TB-500 is not an approved pharmaceutical in major jurisdictions. It is commonly sold as a research chemical for laboratory use, which places responsibility for identity and purity on the supplier and the laboratory. Published human data are limited, and most reports involve preclinical models or cell culture. Questions about whether the fragment mimics all actions of thymosin beta-4, and under which conditions, remain open. Independent verification of any material is therefore a practical requirement in research settings.
TB-500 is a synthetic heptapeptide with the sequence Ac-LKKTETQ. It corresponds to a short N-terminal region of thymosin beta-4, a 43-amino-acid protein found in many cell types. The fragment contains an actin-binding motif, which is one reason it appears in laboratory studies of cell migration and cytoskeletal dynamics. TB-500 is not the full-length protein and is produced as a research chemical rather than an approved therapeutic agent. Its molecular weight is approximately 889 Da.
| Property | Value | Notes |
|---|---|---|
| Molecular class | Synthetic peptide | N-terminal fragment of thymosin beta-4 |
| Residue count | Seven | Sequence LKKTETQ |
| Approximate mass | 889 Da | Acetylated seven-residue peptide |
| Common synonyms | TB4 fragment, TB500 | Not identical to full-length TB4 |
| Reported activity | Actin binding | Observed mainly in cell-free systems |
Identity and purity are checked with reversed-phase high-performance liquid chromatography, which separates the target sequence from truncated or deletion analogues, and with mass spectrometry, which confirms the expected molecular mass. Amino acid analysis and peptide mapping give orthogonal confirmation but are used less often outside specialist laboratories. Counter-ion content varies: material purified on trifluoroacetic acid gradients retains trifluoroacetate, and ion exchange can convert the salt form. Residual water and solvent are measured by Karl Fischer titration or thermogravimetric analysis, and any purity figure should be read together with the method used to obtain it.
Lyophilised peptide powders are hygroscopic, and the fragment absorbs atmospheric moisture when a vial is opened at room temperature. Weighing and aliquoting are normally done quickly in a dry environment, and stock solutions are divided into single-use portions before freezing. Repeated freeze-thaw cycles are avoided because they promote aggregation and can shift the measured content of a vial. These practices are general to synthetic peptides rather than unique to this sequence, but they matter more for short chains kept for long periods.
The seven-residue chain carries several polar and charged side chains, so it dissolves readily in water and in aqueous buffers near neutral pH. No cysteine is present, so disulphide formation is not a concern and reducing agents are unnecessary. Dilute ammonium hydroxide or acetonitrile-water mixtures are sometimes used for stock solutions when initial dissolution is slow. Strongly alkaline conditions and prolonged contact with oxidising agents are avoided because they can modify lysine-containing stretches, and haze in solution usually signals incomplete dissolution or aggregated material.
Animal work has examined the peptide in models of cardiac injury, skin wounding, and corneal repair, with reported outcomes covering cell migration, inflammatory cell influx, and tissue remodeling. Several of those experiments used the full-length protein or longer fragments instead of the seven-residue sequence, which makes direct comparison between reports difficult. Results are generally described as tissue-dependent, and effect sizes vary considerably across laboratories. Independent replication is uneven, so the overall picture is incomplete rather than settled.
Controlled human trials of the short fragment are scarce. Much of what appears in review articles is extrapolated from animal models or from studies of the parent protein, and literature searches return a larger body of cardiac and ophthalmic work on thymosin beta-4 than on the abbreviated peptide. Regulatory treatment differs by jurisdiction, and in several countries the material is handled as a research chemical rather than an approved therapeutic. Statements about human benefit should be read as provisional.
Biological interest in this peptide centers on its relationship to actin dynamics. Thymosin beta-4 binds monomeric actin through an LKKTET motif, and a short sequence carrying that motif can compete with other actin-binding proteins in cell-free preparations. Investigators propose that such competition shifts the balance between filament assembly and disassembly, which in turn affects how readily a cell extends protrusions and migrates. Most of the supporting observations come from cultured cells and purified protein systems rather than from intact organisms.
Material is normally supplied as a lyophilised powder in a sealed vial. The powder is hygroscopic, so exposure to humid air leads to water uptake, caking and gradual loss of the fluffy texture that indicates a good freeze-dry. Vials are best kept sealed with desiccant, protected from light and stored cold. Letting a cold vial warm to room temperature before opening reduces condensation on the contents. Purity is normally reported from a chromatographic run, and that figure applies to the batch as tested rather than to the vial after repeated opening.
Once dissolved, the peptide is far less stable than the dry powder. Aqueous solutions are subject to hydrolysis, oxidation at susceptible residues and gradual loss of material through adsorption onto glass and plastic surfaces. Terminal glutamine can cyclise under some conditions, producing a related species that complicates purity assessment. Dilute solutions tend to lose a larger fraction of material to surfaces than concentrated ones. Buffers, pH and ionic strength all influence the rate of change, so stability figures are only meaningful when those parameters are stated alongside the storage interval.
TB-500 is a research peptide whose sequence matches residues 17 to 23 of thymosin beta-4, a 43-residue protein present in most mammalian cells. The chain is seven amino acids long, written as LKKTETQ, and is normally supplied with an acetyl group on the N-terminus. Suppliers list it as a lyophilised powder under the code name TB-500, and the same sequence appears elsewhere in catalogues as the thymosin beta-4 actin-binding fragment. The label is commercial rather than systematic, so no single authority fixes exactly what TB-500 denotes.
Thymosin beta-4 was isolated from calf thymus in the early 1980s and later characterised as an abundant intracellular actin-sequestering protein. Interest in short synthetic fragments grew once the actin-binding motif had been mapped to the middle of the sequence. TB-500 came out of that line of work as a truncated analogue rather than a natural isolate, and it is now sold mainly to laboratories. Published studies on the fragment have been largely in vitro or in animal models, and controlled human trials remain sparse, so claims about effects in people rest on extrapolation.
Literature and online discussion often conflate TB-500 with full-length thymosin beta-4, even though the two differ in size and are not interchangeable in analytical terms. The fragment is produced by solid-phase peptide synthesis, and the product is a defined seven-residue chain rather than a biological extract. Because the term is a trade-style label, two vendors may supply materials of the same nominal sequence but different counter-ion content, purity, or water content. Comparisons across studies are therefore difficult unless the exact sequence and purity are reported.
=== Education === Kenyon graduated with honors from the University of Chicago with a Bachelor of Science in physics in 1961 as a member of Phi Beta Kappa. As an undergraduate, he developed an interest in origin of life research after attending the Darwin Centennial Celebration in 1959. He then earned his Ph.D. in biophysics from Stanford University in 1965. His doctoral dissertation was titled, "Photochemistry of DL-phenylalanine". After receiving his doctorate, he completed research as a postdoctoral fellow of the National Science Foundation in chemical biodynamics at the University of California, Berkeley, under Nobel laureate Melvin Calvin. He then was a research associate at the Ames Research Center from 1965 to 1966.
== Genetics == The genetics of Bruck syndrome differs from osteogenesis imperfecta. Osteogenesis imperfecta usually involves autosomal dominant mutations to COL1A1 or COL1A2 which encode type 1 procollagen. Bruck syndrome is linked to mutations in two genes, and therefore is divided in two types. Bruck syndrome type 1 is caused by a homozygous mutation in the FKBP10 gene. Type 2 is caused by a homozygous mutation in the PLOD2 gene.
Osteolathyrism, sometimes referred to as odoratism, is a form of the disease Lathyrism. The disease results from the ingestion of Lathyrus odoratus seeds (sweet peas). The toxin found in the sweet peas is (beta-aminopropionitrile), which affects the linking of collagen, a protein of connective tissues. The condition results in damage to bone and mesenchymal connective tissues. Osteolathyrism occurs in people in combination with neurolathyrism and angiolathyrism in areas where famine demands reliance on a crop with known detrimental effects. It occurs in cattle and horses with diets overreliant upon the grass pea. Prominent symptoms include skeletal deformities and bone pain.
=== Polysaccharides === Polysaccharides (sugar polymers) can be linear or branched and are typically joined with glycosidic bonds. The exact placement of the linkage can vary, and the orientation of the linking functional groups is also important, resulting in α- and β-glycosidic bonds with numbering definitive of the linking carbons' location in the ring. In addition, many saccharide units can undergo various chemical modifications, such as amination, and can even form parts of other molecules, such as glycoproteins.
Thirdly and most importantly, IUPAC rejected the name seaborgium for element 106, having just approved a rule that an element could not be named after a living person, even though the IUPAC had given the LBNL team the sole credit for its discovery. In 1997, IUPAC renamed elements 104 to 109, and gave elements 104 and 106 the Berkeley proposals rutherfordium and seaborgium. The name dubnium was given to element 105 at the same time. The 1997 names were accepted by researchers and became the standard.
Sources: en.wikipedia.org
Defense Priorities's Middle East director Rosemary Kelanic pointed out that Trump continually jawboned oil markets to suppress oil prices by calling off his military threats in quick responses to negative financial reactions. Houthi-controlled Yemen threatened shipping in the Gulf of Aden and Red Sea. Its threats had been suspended since 10 October 2025. March threats by Houthi leader Abdul-Malik al-Houthi had not stopped Red Sea traffic as of mid-April, although traffic remained under historic levels after crashing in 2024 as a result of Houthi attacks. On 15 March, the Associated Press reported that the weapons stockpile of the Houthis was running low from repeated attacks on Israel, while Iran had not been able to resupply them, because of the war. Three Amazon Web Services data centers in the United Arab Emirates were struck and damaged as a result of drone strikes, leading to outages of web infrastructure within the Middle East, causing "sparks and fire" as well as "major structural damage" for 2 of the centers, with internal water levels reaching up to 4 cm, worsened by the failure of cooling and air systems. Fundamental web infrastructure including S3 storage, EC2 compute and DynamoDB databases suffered complete outages in early March. Iran shut down Internet access for its people throughout the war.
Magoulick & Marshall (2026) interpret lack of dispersal of pronghorns into South America during the Great American Interchange as most likely linked to lack to suitable climatic conditions in potential dispersal corridors. A study on the limb bone histology and life history of Ampelomeryx ginsburgi is published by Viladot et al. (2026). Quaranta et al. (2026) reconstruct the biogeographical history of giraffids on the basis of the Miocene to Holocene fossil record. Al Riaydh et al. (2026) study the assemblage of giraffid astragali from upper Miocene-Pliocene As-Sahabi deposits (Libya), and identify fossil material of two species of Samotherium (S. major and S. boissieri) that likely differed in habitat preferences. Tsatsalis & van der Geer (2026) reconstruct life histories of Pleistocene Axis lydekkeri and Duboisia santeng from Java (Indonesia), reporting evidence of high juvenile mortality and evidence of survival after senescence. Evidence from the study of the isotopic composition of tooth enamel of deer and Alpine ibex from the Melitzia Cave (Greece), indicative of presence of a Late Pleistocene refugium in the Mani Peninsula, is presented by Tzortzi et al. (2026). Evidence of a flexible dietary niche of reindeer living in Europe from Marine Isotope Stage 5a to Marine Isotope Stage 2 is presented by Hemmingham, Pappa & Schreve (2026). New fossil material of Sinomegaceros ordosianus, providing new information on the morphology of members of this species, is described from the Pleistocene strata from the Yitong River basin (China) by Zhang & Wang (2026).
Malolactic fermentation can aid in making a wine "microbiologically stable" in that the lactic acid bacteria consume many of the leftover nutrients that other spoilage microbes could use to develop wine faults. However, it can also make the wine slightly "unstable" due to the rise in pH, especially if the wine already was at the high end of wine pH. It is not unusual for wines to be "deacidified" by malolactic fermentation only to have the winemaker later add acidity (usually in the form of tartaric acid) to lower the pH to more stable levels.
=== Protandim voluntary recall === In December 2012, LifeVantage issued a voluntary recall of select lots (ten lots in total comprising 247,896 bottles) of Protandim due to potential health risks arising from the possible inclusion of small metal fragments in the final product. In February 2013, the company announced that it was extending the recall to include additional lots of the product, estimating the total cost of the recall at $5.9 million.
=== Museums and exhibitions === Centre for Alternative Technology, Machynlleth Llandrindod Wells Museum National Cycle Museum, Llandrindod Wells Llanidloes Museum Knighton Museum, Knighton Museum of Welsh Textiles, Whitton, Powys Newtown Textile Museum Powysland Museum, Welshpool Judge's Lodging, Presteigne The Old Bell Museum, Montgomery Robert Owen Museum, Newtown WHSmith Museum, Newtown Rhayader Museum & Gallery, Rhayader Wyeside Arts Centre, Builth Wells Y Gaer, Brecon Llanwrtyd Wells Heritage and Arts Centre, Llanwrtyd Wells
Sources: en.wikipedia.org
=== Death of Charles === Charles had been in poor health for some time. After going shopping on a chilly day in Funchal to buy toys for Carl Ludwig, he was struck by an attack of bronchitis. This rapidly worsened into pneumonia, not helped by the inadequate medical care available. Several of the children and staff were also ill, and Zita (at the time eight months pregnant) helped nurse them all. Charles weakened and died on 1 April, his last words to his wife being "I love you so much." Charles was 34 years old. After his funeral, a witness said of Zita "This woman really is to be admired. She did not, for one second, lose her composure... she greeted the people on all sides and then spoke to those who had helped out with the funeral. They were all under her charm." Zita wore mourning black in Charles's memory throughout 67 years of widowhood.
Xerophthalmia, caused by a severe vitamin A deficiency, is described by pathologic dryness of the conjunctival epithelium and cornea. The conjunctiva becomes dry, thick, and wrinkled. Indicative is the appearance of Bitot's spots, which are clumps of keratin debris that build up inside the conjunctiva. If untreated, xerophthalmia can lead to dry eye syndrome, corneal ulceration and ultimately to blindness as a result of cornea and retina damage. Although xerophthalmia is an eye-related issue, prevention (and reversal) are functions of retinoic acid having been synthesized from retinal rather than the 11-cis-retinal to rhodopsin cycle. Throughout southeast Asia, estimates are that more than half of children under the age of six years have subclinical vitamin A deficiency and night blindness, with progression to xerophthalmia being the leading cause of preventable childhood blindness. Estimates are that each year there are 350,000 cases of childhood blindness due to vitamin A deficiency. The causes are vitamin A deficiency during pregnancy, followed by low transfer of vitamin A during lactation and infant/child diets low in vitamin A or β-carotene. The prevalence of pre-school age children who are blind due to vitamin A deficiency is lower than expected from incidence of new cases only because childhood vitamin A deficiency significantly increases all-cause mortality.
All three genes localize to chromosome 19q.13.3 in the order of FPR1, FPR2, and FPR3 to form a cluster which also includes the gene for another G protein-coupled chemotactic factor receptor, the C5a receptor (also termed CD88), which binds and is activated by complement component 5a (C5a) and GPR77, a second C5a anaphylatoxin chemotactic receptor C5a2 (C5L2), a second C5a receptor of debated function which has the structure of a G protein coupled receptor but fails to couple to G proteins. These points are of interest because C5a is generated by the interaction of bacteria with blood plasma components to activate the complement cascade which then cleave C5a from Complement component 5. Thus, bacteria produce a family of oligopeptide chemotactic factors plus activate host complement pathways to generate C5a, which, like the formylated oligopeptides, is a neutrophil chemotactic factor that operates through receptors whose genes cluster with those for the three formyl peptide receptors. Furthermore, bacteria-induced complement activation also causes the formation of complement component 3a (C3a) by cleavage from complement component 3; C3a is a neutrophil chemotactic factor which operates through a G protein coupled chemotactic factor receptor, the C3a receptor, whose gene is located at chromosome 12p13; C3a also acts through C5L2.
Histology (also known as microanatomy or histoanatomy) is the branch of medicine that studies the microscopic anatomy of biological tissues. Histology is the microscopic counterpart to gross anatomy, which looks at larger structures visible without a microscope. Histopathology is the branch of histology that includes the microscopic identification and study of diseased tissue.
Sources: en.wikipedia.org
No. Thymosin beta-4 is a 43-residue protein, while TB-500 refers to a seven-residue fragment corresponding to its N-terminal region. The two names are often used loosely in commercial and community writing, which obscures the difference in size, sequence, and likely behavior.
The fragment contains an actin-binding motif, and cell-free experiments show that it can interact with monomeric actin. That observation is the basis for interest in cell migration and repair processes. Effects reported in animals are not established for humans.
Purity is usually stated by the supplier rather than fixed by a pharmacopoeial monograph, and typical listings report a percentage from reverse-phase HPLC. Independent verification is uncommon. Because no single accepted specification exists, comparisons between lots and between suppliers are difficult.
TB-500 is a synthetic heptapeptide corresponding to a fragment of thymosin beta-4. It is used in laboratory research and is not an approved drug.